EMC Question of the Week: July 29, 2019

metal sheets

Which of the following materials could not exist in the real physical world?

  1. Flexicon (σ = 0.001 S/m, εr = 2, μr = 1)
  2. Plastipure (σ = 10-5 S/m, εr = 0.4, μr = 1)
  3. Magnemite (σ = 2x105 S/m, μr = 10,000)
  4. M-alloy (σ = 2x106 S/m, μr = 1)

Answer

The correct answer is "b". Real materials have relative permittivities, εr, and relative permeabilities, μr, that are greater than or equal to 1. A relative permittivity of εr = 0.4 implies that the permittivity of the dielectric is less than that of free space, which is not possible.

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